It is important to understand that, with Joomla!, the content of the site (for example, Articles) is totally separate from the formatting of the site — the way it looks on the page. So it is best to think of articles as pure content, independent of the way it might be presented. For example, the same Article might be shown with different fonts, colors, headings, and background, and might be shown in different locations on the page.

Source : docs.joomla.org

To insert a module inside an article, use the {loadposition xx} command, as follows:

1. Create a module and set its position to any value that doesn’t conflict with an existing template position. You can type in the position value instead of selecting it from the drop-down list. For example, use the position myposition.
2. Assign the module to the Menu Items that contain the articles that you want the module to show in. You can also just assign the module to all Menu Items.
3. Edit the articles where you want this module to appear and insert the text {loadposition myposition} in the article at the place where you want the module.

Note that this only works when the Content – Load Module plugin is enabled. If this plugin is disabled, the text {loadposition myposition} shows unchanged in the article.

Source : docs.joomla.org