What many call or ask about guns finish is not a finish but a "metal treatment and no Glocks or any guns made in USA ever had Tenifer treatment since outlawed here due to containing Cyanide, Glock used Melonite on USA made guns but stopped using it in 2010 and now use a cheap metal treatment followed by a cheap finish and as of 2010 Glock's have tons of complaints about finishes scraping/flaking and wearing off very quickly, so they now offer a Optional finish, they are actually now the worst finish of all major guns!
Fortunately my early Glock. Walther etc.. have Tenifer and were made in Austria/Germany.
Tenifer/Melonite/Arcor/Nitride are a "Metal Treatment" and not a finish all of thes treatments will impregnate the metal for a few thousand millimeters and thus offer great rust protection, however any gun thus treated Can Not be touched up with Gun Blue, since it wont penetrate the metal!
CZ uses Polycoat over a Arcor/Melonite finish, Polycoat is an electrostatically applied pieces of Polymer which then are baked on and currently is a great finish but somewhat dull.
The best way to reduce wear on any gun finish is use a good Leather holster and never Kydex.
The best gun finishes are as follows!
1) Chrome, but looks pimped so get blackened Chrome.
2) Nickel, hardly used anymore but can flake/chip over time.
3)Stainless Steel, actually not a finish since its in metal, but usually a Inox (great) finish is then applied and can be buffed for scuffs/scrapes.
4) Park.
5) Good Blue.
6) Polycoat types.
Lately many major gun makers offer Cerakote (which I will never buy or have put on a gun, some like it since it is a sprayed on finish then cured and can be used on plastics also like gun stocks/ grips but will wear/flake easy and look like ****, cant be touched up but entire gun needs to be refinished.