Hmm, if you found it in the sofa, that either implies they're feeding on the dust/food that has fallen between the cushions, or they're eating the wood (so could be woodworm after all!).
The key thing is the 'where'. Woodworm tend to leave little 'sawdust' piles outside the holes that they've excavated. If your sofa is on wooden floors it would be easy to spot these. However, if you can pull out the cushions and find them scurrying around where 'stuff' has gathered (crumbs etc), then it's more likely to be food beetles.
Standard insect sprays will work, but if you see any exposed wood with holes, then you'll need some of the woodworm 'paint'.
95% of home insecticides will be pyrethroids, which are relatively harmless to kids and animals. They're not quite as good as the industrial insecticides that say Rentokil will use, but they act quicker. Go for anything that says fast acting and it will be what you need, but if in doubt, look on the ingredients list and if the chemical ends in '-thrin' you're set :)
It will say something like 'contains 5% w/v cypermethrin'. Try to hold your breath when spraying, and if you're giving more than a quick spritz, maybe leave the room for an hour after to be safe.