Plastic fittings used down a well is a bad idea. SS or brass with extended length barb is best.
No 'glue' will stick to PE anything.
Overheating the pipe, or not heating the inside and outside evenly, and over tightening the hose clamps, tightening the clamps when the tubing is hot/warm, and not checking the clamps for proper tightness after the pipe is cool, are the primary causes for joint failure.
Most places selling the pipe or hose clamps will have a T handle ratchet type torque wrench for the clamps. You should never tighten them until the screw can't turn.
What rating pipe are you using? It should be 160 or 200 psi. Less is probably too soft and possibly stretching due to the torque of the motor.