I've done a bit of prototype work and a lot if injection molding of Acetal (Delrin is tm). I never have bonded parts but if I can explain this, have created a mechanical "lock" made of epoxy.
If you have a shaft in a bushing. Groove the i.d. of the bushing and at the same location, groove the shaft. Assemble with those grooves full of epoxy and at the right location. You essentially have a solid o-ring and neither part can move. I've done that with a lot of dis similar materials, no threading and it doesn't take much of a groove.
Delrin doesn't absorb much moisture but for heat resistance and electrical situations I have used Ultem. Very machinable, good temperature resistance, expensive but I use onlinmetals and they cut short pieces. Ten buck for a foot of 1" dia.
I am new to forums, can I mention a supplier??