Spark plug insert came out with the plug

[James Phillips]

I changed spark plugs on Edmunds aluminum heads. I had a steel spark plug insert come out with the plug. Am I right this was put in to repair a stripped plug hole? I tried getting the insert off the old plug with solvent and heat but can't without buggering up the threads. Where can I get another insert? Then I could put a new one back in with red Loctite. Any help appreciated