index of N highest elements from a list of numpy array

I need a function that returns the index (row and column) of the N highest element from a matrix/list of numpy array.

Suppose that I have the following matrix:

a = [[4,2,3], 
     [5,0,3]]

I would like to get a list of the indexes (row,column) of the N highest elements. For example, if I want the index of the 4 highest element, the function should return

[(1,0), (0,0), (0,2), (1,2)]

I have tried implementing this as following, but it returns a list of (value, row number), which is not want I need

for i, sub_list in enumerate(a):
    max_list.append((max(sub_list), i))