I've recalled another maybe much more better* solution for matrices: in Word, select Insert | Equation | Insert New Equation. Then when your new equation is selected and the Design tab on the Word's Ribbon is activated, select Matrix | Empty 2 by 2 Matrix in Brackets. From the matrix context menu of your matrix, insert rows and columns to your matrix.
* I do not know how to add row and column numbers outside the matrix. Again, I can suggest solution: insert data in your matrix, then make screenshot from your document using standard Windows Snipping Tool, select only your matrix and insert it back to Word as picture. After that, for this picture from the context menu call Size and Position, in opened dialog in the Text Wrapping tab select Square option. After that you can move the picture within text and pick up font and paragraph size and insert rows and column number: See on picture