Borewell with silt in Bangalore, Karnataka - Need advice regarding the type of pump to be used

Iam situated at mahadevapura, Bangalore. I am facing a recurring problem of silt in our borewell. The depth is 550 ft with installation of  2HP submersible pump/ 22 stage from  Sugana Pumps. The water standing level is 40 ft, the depth of motor immeresed is 500ft. Every 4-6 months either the motor jams or the pump impellers get jammed, hence have to lift the unit repair the faulty part of the motor pump &  run again as usual. Now this become a costly affair to maintain the bore well.

So please suggest/recommend a solution for my problem as to whether the pump type is to be changed or use a different technology to pump the water along with silt without recurring maintenance expenditure.