I own Colt, Kimber and Para Ordnance 1911's. Without question, my Paras have been the best. Out of the box, both had great triggers, digested every ammo I fed them without hiccup, and were remarkably accurate. My SSP (traditional single action, single stack, full size 1911) was also a smokin' value at $595 brand new about three years ago.
If you had a "regal" finish (black Para-Kote) LTC, the parts you refer to are indeed not stainless steel, but Para never advertised them as stainless (Para makes stainless steel guns such as my CCW, but many of their guns are made of non-stainless with a Para-Kote finish, and the catalog clearly identifies which are which). Some of the small parts on Regal finish models, such as the grip and thumb safeties, are finished in a silver/gray Para-Kote to contract with the black Para-Kote of the frame and slide. They are not "cheap plated metal of some type" and are not plastic. They are MIM (molded) steel with a heat-cured finish applied, which is a technology commonly used by many gun manufacturers, including Springfield Armory and Kimber. I'm sorry to hear that the finish started to come off yours. You may have gotten ones that weren't cured properly, or that were contaminated with something prior to the finish being applied. If so, Para should have replaced them under warranty. The finish on my SSP, including the silver parts, still looks new despite thousands of rounds through it.