\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{decorations.markings}
\begin{document}
\begin{frame}[t]
\frametitle{Placing pics along a function}
\begin{tikzpicture}
\draw[blue,very thick,postaction={decorate,decoration={markings,
mark=at position 0.1 with {\node{\includegraphics[scale=0.3]{example-image-a}};},
mark=at position 0.5 with {\node{\includegraphics[scale=0.3]{example-image-b}};},
mark=at position 0.8 with {\node{\includegraphics[scale=0.3]{example-image-c}};}
}}] plot[variable=\x,domain=0:540,smooth,samples=31] ({\x/50},{2.5*sin(\x)});