Vesconite people will customize you a bushing if needed, so maybe the wood bush is to accommodate an odd size. They are solid vesconite, so they can be machined to fit. Vesconite is also self lubricating, to a point of course. I doubt it would survive with no water flow in a fast high pressure shaft. But they do make that point.
If you use GFO packing, then you can be dripless with a standard packing gland housing, no need for anything fancy, just better packing. It also lasts a long long time.