Yes, pdfTeX embeds fonts (or their subsets) into the document. (How would the PDF be portable amongst computers if it referenced external fonts?) You can verify this in your PDF viewer or with the pdffonts utility (look at the emb column):
% hello.tex
\documentclass{article}
\begin{document}
Hello World
\end{document}
> pdffonts hello.pdf
name type emb sub uni object ID
------------------------------------ ----------------- --- --- --- ---------
RRGCUS+CMR10 Type 1 yes yes no 4 0
The only special case is the so-called Base 14 Fonts, which are required to be present in any PDF reader. Technically they could be omitted from inclusion when generating the PDF. But, as the PDF reader could use a substitute font (like Nimbus Roman No9 L for Times), some people prefer to force the inclusion of the base 14 fonts, too. In fact, this is the default behaviour in TeX Live (and could well be elsewhere).
If you find that the default 14 fonts are not included, locate the web2c/updmap.cfg configuration file in your system or local TeX distribution configuration directory and change the pdftexDownloadBase14 line to
pdftexDownloadBase14 true
Then run updmap (for local changes) or updmap-sys (for system-wide changes).