Try UHMWPE. This is ultra high molecular weight polyethylene. It has outstanding sliding and wear characteristics. One example is railroad coupling wear plates. Hardened steel wore out in a couple of months. UHMWPE lasted for years.
One thing to be aware of when selecting a polymer for a wear slide is water absorption. UHMWPE has good water resistance and is often cost-effective, but if the UHMWPE wears too quickly or melts, you may want to try PTFE (TEFLON). It is more costly but has a lower coefficient of friction and may withstand higher temperatures.
Dupont has a material that is commonly known as Delrin. It's sturdy, can be machined and molded, and works well as a sliding member. "Happy the Hare at morning for she is ignorant to the Hunter's waking thoughts."
You could also try Thordon. This urethane elastomer is a bearing material sold by Thomson-Gordon of Burlington, Ontario, Canada. It is used to line sheaves for ski-lifts and create stave bearings for ships propeller shafts among many other applications.
Thordon is used to replace uhmwpe and delrin due to its superior wear resistance and ability to resist "pounding out".