If you know the page ID, the simplest answer would be to get the content for the page.
// This retrieves the content from the post or page where ID = $page_id.
// You can either set this above here, or call get_the_content(12). Your choice.
$parent_page_content = get_the_content($page_id)
// Clean it up and make it a bit more legible:
$parent_page_content = str_replace(']]>', ']]>', $parent_page_content);
$parent_page_content = apply_filters('the_content', $parent_page_content);
// Now echo out the content in place! <p> tags won't be necessary here, btw.
echo $parent_page_content;
This method doesn’t interfere with the loop at all, so you won’t need to use wp_reset_query() after doing this. Also, because you’re applying the the_content filter to your text, it’ll automatically add the paragraph and break line tags for you.
Hope this helps.