If you wish to make actual "wear parts" from it, either Acetal co-polymer or UHMW polyethylene are good candidates.
Avoid the Acetal in the homopolymer version in any sections more than about 3/4" thick... they suffer from porosity in the center. Both have essentially the same machining characteristics, which are fine surface finish, and "free machining" in terms of clearing chips and lack of tendency to heat. It's also much stiffer and heat-resistant than polyethylene.
Type I PVC is also reasonably easy to machine well, but you must keep it cool or it tends to melt onto the tool edges. It's great for moderate wear, where you need especially stiff components.
LLoyd