jmusg
criteria are material being conveyed; size amount hardness abrasiveness wet/dry. Gypsum is not too harsh.
Area to be lined ; large / small; is it accessible for reline; critical use ; is there going to be much impact or is it mainly sliding abrasion.
If impact is not a problem, I'd use ceramic tiles; sometimes I have prefabbed them onto a steel plate for quick installation; also good is chrome carbide overlay plate.
If theres a lot of impact then consider rubber ceramic.
In the worst instance ( not yours ) then one of various grades of steel plates are used .
Abrasion Resistant steel plate is frequently used as a standard; it's relatively inexpensive and if the life is ok then thats good.
An advantage of the polyurethane liner in some instances is that in some instances it's better if material builds up; also it's quieter than steel if that's a problem.
A lot of the time it comes down to what's worked in the past and of course cost. Lead time is another factor; if something has to be repaired to day then steel is often the material of choice because of availablity.
Another factor is that for instance in a chute or hopper, the bottom may experience differnt wear than the sides, so you can use different grades / materials/ thickness to keep costs down.
hope this helps
mac