i've tried it but it's not a good idea since differential wear on the soles will still be a problem regardless of the extra cushioning you would get from the new insoles. This could lead to injuries.
As an experiment, i put on a new running shoe on one foot and on the other foot, i put on the worn down running shoe with a new insole. I could most definitely feel the difference and i was not getting a level platform on the old shoe because one side of the soles were worn more than the other as was the heel.
One thing i have done, though, is to swap out the insoles of some lighter weight running shoes with more cushiony insoles just so i could use the light weight shoes as more regularly as comfortable everyday trainers.