Impeller,if aluminum,is about $140-$150 the last I checked. The sleeve is aluminum,and run $40-$50 They should be pretty easy to find,
Try to keep your impeller sharp,and the sleeve smooth.
You should shim your impeller so its as close to the sleeve as you can get without rubbing.
Whoever you get the parts from should be able to give you some pointers on doing this.They are actually pretty simple.