Deep well pumps are designed to draw water past the motor to cool them. When installed in a tank, sometimes you have to put a shroud around them to maintain that cooling pattern. If the screen plugs and the pump runs without water flow, it overheats and goes bad.
Regardless of what type of pump you install, your first order of business should be to figure out a way to keep the sand out of the pump. Draw your water from a level off the bottom and away from the sand source as much as possible. Expand your intake out to as large a intake as you can to minimize the velocity. A large radial screen or box screen at the end will help with this. You might also put a sand diverter fitting in the inlet pipe, but you'll have to either set this up to automatically clean, or manually clean it periodically. A screen box with a lot of screen surface area so it can't clog would be a good idea also. One made with triangular wire won't clog as easily as a mesh wire screen, and self cleans when the pump goes off and the water velocity drops. What you'll find is it is usually the smaller sand size that mobilizes upwards enough to get into the pump, as long as your intake is designed to minimize velocity. Analyze the sand size that accumulates in the spring box, and have the screen sized for the 95th or 98th percentile sand size. I have a Edmund optic pocket comparator with a sand size reticle that I use for doing this, but before I got that I used a dial caliper and a microscope.
