You will not be able to fill the well with water. Any well that will make water, will take water. The water level will stay the same no matter how much water you put in it.
The styrofoam that is still in the well, should not affect the well. When you pulled the pump, you more than likely got 90% of it out. It will float on the water.
If you need to get what is left out. You could try to blow it out with an air compressor. It would need to be a decent sized one. 100 or 185 cfm. Most air compressor that size will be trailer mounted. It take volume not that high of pressure to blow a well.