using Overpass Turbo I can see there are 6 nodes tagged as natural=well, all in the UK (specifically lancs/yorks)

https://www.openstreetmap.org/node/664011272
https://www.openstreetmap.org/node/664011975
https://www.openstreetmap.org/node/664012000
https://www.openstreetmap.org/node/664435202
https://www.openstreetmap.org/node/664143524
https://www.openstreetmap.org/node/3770729905

I'll DM the user who created these as he may have since changed the way he maps these