I'm trying to create a work breakdown structure for a project and am having difficulty in getting the correct spacing between the nodes.

Below is the required result:

This is my current script:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usepackage{lscape}

\begin{document}
    \tikzstyle{ss} = [rectangle, minimum width=2cm, minimum height=1cm,text centered, draw=black]
    \begin{landscape}
        \centering
        \begin{tikzpicture}
            \node (start) [ss] {Development of "New Product"};
            \node (PM) [ss,yshift=-1.2cm] {Project Management};
            \node (MA) [ss,right of = PM,xshift=2cm] {Market Assessment};
            \node (C) [ss,right of = MA,xshift=2cm] {Commercialization};
            \node (D) [ss,right of = C,xshift=2cm] {Design};
            \node (E) [ss,right of = D,xshift=2cm] {Engineering};
            \node (EQ) [ss,right of = E,xshift=2cm] {Engineering Quality};
            \node (P) [ss,right of = EQ,xshift=2cm] {Procurement};
            \node (SQ) [ss,right of = P,xshift=2cm] {Supplier Quality};
            \node (M) [ss,right of = SQ,xshift=2cm] {Manufacturing};
        \end{tikzpicture}
    \end{landscape}
\end{document}

Which produces the following output:

I would like to have the text wrapped in the nodes as well, but am not sure how to go about this.