Epoxy (the 2 part stuff).
Clean/sand the edges of the insert and the hole to remove old glue and residue. Then apply the epoxy to both and press into place. Use something flat like a wood block to set it at the right height.
Oh.. I guess I should mention that this advice assumes you're removing the insert first. If not, I guess you can back fill it with epoxy as well and then heat up the insert with a hairdryer and just push down... but it's not as good of a fix.