Miele now considers W1918 and several other models from 19XX series "obsolete". That is production was discontinued and things have gone past the 15 years Miele promises to provide NOS parts.
Miele no longer imports parts from Germany for most if not all W19XX washers along with all W1070 and W1065. Whatever is in their warehouses is all she wrote, once that supply is exhausted that is that.
Sometimes a tech or authorized repair service may have stash of NOS parts that Miele can access, but if that option fails, then that's that.
Have a Miele washer older than yours and can tell you "your machine is old, replace it" is Miele USA's standard response when it comes to repairing older washers, dryers and other appliances.
That being said if one is clever and is willing to spend time and effort, there are ways to get around Miele.
While Miele does make many parts for their washers and other appliances in house, certain others are sourced from various vendors. Pumps for washing machines and dishwashers are one such part.
Hanning did indeed supply pumps for Miele washing machines, so you're on the right track.
Your washer is 120v/208 (240v)v, but IIRC very little under hood of Miele W1918 washers ran on 208v/240v. Pump runs on 120V which means anything from Europe or elsewhere in world at 208v/240v won't work.
You just missed a used W1918 pump on eBay.
https://www.ebay.com/itm/274822290951QUE...
Would this work?
https://www.ebay.com/itm/313673884335QUE...