Use the localpart of the DArray while assigning, this makes it explicit that a process only assigns to the section allocated to it.
julia> remotecall_wait(D->localpart(D)[1,1] = 0,2,testD)
Future(2, 1, 117, nothing)
julia> testD
5×5 DArray{Int64,2,Array{Int64,2}}:
0 3 4 5 6
3 4 5 6 7
4 5 6 7 8
5 6 7 8 9
6 7 8 9 10