Wow, this is a big topic but I’ll answer it quickly. Yes, in fact WordPress is so search engine friendly, if you have done all the rest right, that is it astounding. But you have to do the rest right.
1. Watching your page ranking is like following the stock market. Do it every day and you will get ulcers. Do it every month or three and you will have a clearer idea of how the whole thing works.
2. Make sure you have titles and alts on all images and links and that the words in them match the keywords and words within your content. Same with headings.
3. Make sure you are not using tables, links and page display inside of javascripts, flash, or other things that aren’t TEXT but which display information. If you do, then make sure there is plenty of text to back up your keywords and site purpose because search engines can only read WORDS not pictures.
4. Make sure you have your most important information in the first third of your page. ALL of your page, coding and all. Try to push things “up” – but that is a more complicated issue. Some search engines troll only the first 30-50% of a page.
5. Research your keywords and use them very wisely. There are tons of articles on the net about this or you can try this article for more info.
6. Learn everything you can about how search engines work, how they work together and separately, and as soon as you do, they will change the rules. But start at https://www.searchenginewatch.com/ and selfpromotion.com.
I hope this helps. Being scanned by s search engine isn’t a guarantee that you will be included. They have a lot of criteria that goes beyond the scope of WordPress. But we are working on an article in the Codex that will be released soon on how to make WordPress even MORE search engine friendly. Stay tuned.