as I said, I'm no specialist. The only thing I know is from aviation magazines and the aircraft I made conversion training on.
As I remember, composite structures are made in layers. Depending on the technology, the use and the strenght, they include metals like Aluminium, Magnesium and Titanium. Or any blend of it.
I also remember in an old Mirage III where the honeycomb structure was made of metals, i.e. the comb itself was made of very thin metal sheets.
On the 787 you have additional technologies: Bolts, hinges and any sort of conections are put into the resin structures. On the A350 they want to have similar sandwich structures, but with more metals in it. I can imagine that they will just include more layers of metal instead of kevlar/fibreglass/other fibres. They are mainly talking about Magnesium, but so far design is not yet freezed.
If you want to know more, try Wikipedia, e.g. under "Glare" ("GLAss-REinforced" Fibre Metal Laminate).