True, cast iron does wear very fast, so the next best thing is to get bronze worm gears and steel worms, both which you can get at SDP-SI
https://sdp-si.com/eStore/
They have both smaller nylon worm gears (perhaps too small), but larger bronze worm gears which I think would suit your application. If you do order from them, please order as soon as you can because our team has had some trouble with delayed shipping (in our case, gear stock).