The washout base and pitch block are only about $3 USD at HeliDirect. They seem to be good for about 50 to 60 flights from what I read and found. Polishing the edges and flat track of the slot will help with wear, but gently twist the main blades up as if under positive pitch stress and the washout base tilts and causes a diagonal load on both parts. Also, when the swash tilts, the washout base wil beat around in it's slop from the changing blade angles. A metal washout base may help, and keeping a film of silicone grease under the washout base (ring) and in the pitch block slots will be even better. That situation will be tricky in any case other than a washout base with a precision fit linear bearing. I made a lot of money reparing cheap robots made with a similar technology, only bronze instead of plastic.
No one makes a washout base with linear ball bearings built in. That may cost at least $20 USD to make.

CH