How about a packed column made of five gallon buckets connected in a series hung from a u post over your well? You pump the water up a few feet to the top bucket and it drops through via gravity through each bucket packed with plastic media.
That's what I do for my trout pond and what many trout farms and even state and federal facilities that raise trout do. Not only are you aerating the well water you are blowing off nitrogen gas, carbon dioxide, and hydrogen sulfide gas which are bad for your fish.
The buckets have cutouts in the bottom that with a shelf left are lined with plastic screening (as used in fish cages) to keep the media in and allow water to drop through. The very top bucket has a plastic piece with holes in it to distribute the water evenly.
D.O. saturation goes from almost nil to 90 percent by the time the water hits the pond.
Here are some pictures. Notice the iron in the water has discolored everything.
Top bucket of the series.
Different view of top bucket.
Again different view.
Plastic media:
My well water is introduced from a 6 by 6 pit after the packed column (not necessary for one pond as I use it to divert water via gate valves to the pond of my choosing), and then underground via a 4 inch PVC pipe to the trout pond. At the trout pond it's introduced at the surface with an upturned elbow to get further aeration.
The idea of introducing aerated well water to the bottom of a pond makes sense but I've never tried it.
How large is this pond again and what is the average and maximum depth?
A few trout from my trout pond:
