Personal experience in a full Hardcore group around level 30 to 35 and throwing a level 45 (Tier XII) item into a well ... the person (Andy aka Kalms) threw in a Tier XII earth charm and got instantly killed from the monster that spawned. I as the Guardian in the group Healed up the other members to exit the catacomb and I was lucky enough to survive and exit as well.
Now, during that time, you could not "Edit" your group, and you had to have a minimum of 2 active players that had bridging characters to have a level 80+ guardian tank/healer in the group, and the other 4 members had higher level characters to join the group and kill off that one monster that spawned from throwing in that white Tier XII earth charm. and I stayed at my level 30ish and was a back up healer.
Results was a 165% Enhanced Effect Tier XII Earth Charm that I still have to this day, but, without the help of others then, this item would not be around.
Oh, yup, during the time that a Well only appeared in catacombs, not the Well that used to be in Town. Just a clarification to older players.
At OP... wells are good, you just need to learn how they can insta kill you, or they just constantly die and give you junk crap items.