Every phone will get micro abrasions so it’s only natural, it is a bit more noticeable on the “black” iPhones. If you want to protect your phone from scratches, buy a full edge to edge screen protector, a camera protector and a good coverage case. There is no avoiding micro abrasions as the phone screen is a level 6 hardness on mohs scale which can be scratched by some metal dusts, but it should be safe from your keys. To answer your question, all cases will protect your phone from the abrasions to some degree, some better than others. Just look for one with back coverage and buy a screen protector.