I've been through this a few times since I bought my house around 1992. I have a shallow well with water at about 20'. I use a shallow well pump. Jet pump is needed for lower water levels to create a low pressure area to increase suction in the pipe. The other option for deep wells is a submersible which can go down hundreds of feet, and push water up instead of using suction. They use a pitless adapter below the frost line.
In the early years I would call the plumber, but quickly learned to deal with the basics. I keep a new spare pump and foot valve at all times.
The first sign I get is a bit of air spitting out with the water. Losing prime is the main thing. It is usually due to a leaking foot valve. I just put in a new one yesterday. In my situation they last about 7 years. I get my neighbor over, we pull out 35' of poly line, install new foot valve and drop it back down. It takes a little over a gallon of water to reprime the line.
I had one occasion where the pump was air bound and running dry and burned the pump impellor out. My wife and I had jut come back from vacation, she took a shower and yelled to me the water pressure was dropping fast. I had her turn off the shower and I ran to the well. Changing the foot valve takes a half hour. New pump install takes about an hour. She was able to finish her shower.
The other thing to watch for is the well tank. If the internal bladder fails and it fills with water, the pump will short cycle. That can severely shorten the pump life. Well-X-Troll is a top brand. Cheap ones can have a much shorter life span. Getting the tank size right is important. Too small and it cycles the pump a lot, too large and you spend a lot of time with low water pressure before the pump kicks in. The tanks air pressure needs be 2 psi lower than what the pressure switch low cut in is set to.
My well originally was an 8'x8' five feet deep with a basic lean-to structure about 25' from the house. I built a garden shed over it with an access panel and ladder down to the well. I have the pump, pressure tank, particle filter, sump pit, and water softener in it. The pipe is copper with heat trace and insulation over it. Temperature generally can go down around 0 degrees at the worst, like this past 2 weeks. The lowest I've recorded in the pit is 37 degrees, but generally is around 42 degrees in winter.
