4/2014 I replaced all brake parts. ALL. Hubs, shoes, calipers, etc. Just last week I barely heard a small scraping. Wife and I pulled the front wheels and pads were surely worn. Found one pad bad and it had rubbed rotor. When I pulled calipers I find badly worn and rusted cylinders. Took then to OReilly and they replaced both under warranty. Photo shows new cylinders and all old parts. It appears there is some kinda insert on head of cylinders that is wearing. What gives?