This is quite common and pretty harmless. The scratches you see don't go very deep, nor are they very wide. My All-Clad saute pan is nearing 10 years old and has a ton of micro-scratches on the interior. It still performs beautifully.
That said, the scratches can grab onto proteins and cause sticking. However, this is simple to prevent with both oil and proper pan preheating.
When a pan is preheated properly the metal expands, essentially closing all of the micro-scratches. This prevents the proteins from grabbing onto them and getting stuck. You obviously need oil/fat to assist with this as well.
To properly heat a pan to the appropriate temperature I suggest using the water drop method. If you put a cold pan on heat and drip a drop of water onto it, the water will sit there for several seconds then boil away. As the pan gets warmer this will happen more quickly, fizzling away in a second or so. Once the scratches start to close something weird happens.
First, the drop of water will break into a few mini drops which scoot around the pan as they evaporate. This is a sign that you are almost there. When the drop of water stays whole (mostly) and scoots around the pan like a mercury ball, this is the perfect temperature. I the water instantly vaporizes on contact, you've gone way too far and need to let the pan cool down. At this point you should add your oil/fat, swirl it around, and immediately add your food. (Make sure the mercury ball of water is gone before adding oil).
Also note that the mercury-ball phase is definitely too hot for unclarified butter, and may be too hot for some extra-virgin olive oils. They may instantly smoke upon adding.
Again, it's important to have your oil and ingredients in place (mise en place) before you start. It's quite easy to skyrocket past the mercury-ball phase if you have to open your oil, pour, and then season your ingredients.
I used to have this fish sticking problem in my Aluminum wok.
The solution (accidentally discovered) was to put the fish in the wok only after the oil is hot enough.
Que: How do you decide whether the oil is hot enough?
Ans: Drop one Yellow Mustard Seed in the oil. If it cracks immediately then your oil is hot enough for the fish to be dropped in. If not, then you may like to wait for few more minutes and try the same with another mustard seed.
Yellow Mustard Seeds start cracking in very hot oil only as opposed to Cumin seeds which do turn brown in non-so-hot oil too.
Best Answer
First things first, make sure you're keeping that pan on high while the haloumi is in there... you can get the pan as hot as you want, but the water in that cheese will cool it off right quick.
Though in my experience, sometimes halloumi just sticks. When I'm cooking something potentially sticky, I always have a nice-quality, even, sharp fish spatula on hand in case I need to save it. If you really put some pressure on it, scraping along the bottom of the pan like you're removing a sticker from a window with a razor blade, you should be able to save your nice sear. As long as you're applying even pressure and using a flat bottomed pan and have a nice quality fish spatula, you 'shouldn't' gouge it... though that's the reason I use heavy commercial steel cookware from companies like Winco, which I could replace pretty easily and cheaply. ;-)