Wheel nut threads

[ianrandom]

Two of the bolts on my back wheel hub are not screwing in tightly, the thread seems knackered on the hub.
Is it possible to get an insert put in these? A Helicoil or whatnot.
Or if not, is it a big job to change the rear hub? I do have a spares car i can cannibalise if necessary at some point.
Thanks in advance for much appreciated wisdom!

 

[ianrandom]

For reference, a tap and dye set was the fix for these, as they werent too bad.