Space between emphasized word and parenthesis

I can't really see the J touching the parenthesis, but I do agree that the output is ugly. I find it ugly since the space between ( and W is much larger than the space between J and ); in fact, in my opinion this first space is much too large. The problem is that there is an italic correction after the J, so that there is at least a little space between J and ), but there is no sort of correction before the W. Look at the bounding box of the italic letter W to see the problem:

It is the white space in the left of the bounding box that makes WSJ look not centered in the parentheses. I'm afraid there is no clean solution for this, so you have to use manual spacing corrections, as Harald proposed. I find that (\!\emph{WSJ}) yields much better output:

(See also this question of mine that deals with the same problem in the definition of the italic fonts.)

Yes, it does. Compare with ({\em WSJ}) which adds no italic correction. If the italic correction is not sufficient, you may wish to add a small bit of explicit \hspace yourself.

I also think that the italic correction after J is appropriate and that the missing negative kerning in front of W is responsible for the suboptimal output. If you use pdfTeX (PDF- or DVI-mode) you can cope with this problem (and similar ones) by means of the kerning feature of the microtype package:

\documentclass{article}

\usepackage[kerning]{microtype}

\SetExtraKerning[context=pemph]{encoding={OT1}, shape=it}{W={-150,}}

Now, you can define a command \pemph automatically taking care of the desirable kerning in front of W which results in a better centring of \emph{WSJ} inside the pair of parentheses:

\DeclareRobustCommand{\pemph}[1]{%
  (\emph{\microtypecontext{kerning=pemph}#1})%
}

\begin{document}

\noindent
\pemph{WSJ}\\
(\emph{WSJ})

\end{document}

The resulting output is:

Note that the microtype package is designed to work with both pdfTeX and luaTeX. The kerning feature is currently only available for pdfTeX, though.