I used it to build up a wear surface on a pot metal VW door handle once. Actually, laminated layers of JB Weld and beer can aluminum with the last layer aluminum.

It's also holding coolant in the Massey Ferguson's cracked water jacket.

Cast a new weed eater cutter head...

It machines easy but because of this I don't think it would wear well. How about a brass insert surrounded by JBW?