My jet is right on the nose of the pump. It is cast iron and bolted right on the impeller casting. If you are raising the water over 20+ feet the jet may have to be at the bottom of the well. Most people use submersible pumps now and they are in the well at the end of the the supply line. I am guessing that doesn't work well in a lake.
Actually I went from a jet pump to a submersible pump to to a county rural water district. Now I don't have to deal with pumps at all. Well almost anyway. I left my outside hydrants on the well for watering and such.
Swimmer, is your pressure switch a 20-40 or a 30-50? It should say somewhere on your switch cover. 57 may be all you can get out of your system for a variety of reasons. Lift, suction line size, impeller wear, etc, etc. If you have 57 psi at static, what do you have with water flowing?